I have rewritten /FOSTER/bin/tigcmproc.dev with option to plot
4 additional fields: o/o2, o/n2, o2/n2, and o/(o2+n2). Please
add these fields to your FIELDS lexical read. It should now
look like this:

C
C          tn  un  vn  o2  o1  n4s  no  o+  n2d  ti  te  ne  o2+  w  z
 FIELDS =   0,  0,  0,  0,  0,   0,  0,  0,   0,  0,  0,  0,   0, 0, 0,
C          pot  n2  ui  vi  wi fof2 hmf2 rho unvn uivi o/o2 o/n2 o2/n2
             0,  0,  0,  0,  0,   0,   0,  0,   0,   0,   1,   1,    1,
C          o/(o2+n2)
             1

Also, if you use CMIN, CMAX, CINT, the new fields will have to
be added to those lexical reads. 

The ratios are calculated after any conversion of composition
determined by IDEN. Also, any height interpolation or averaging
(e.g., zonal or global means) is done after IDEN conversion and
after the ratios are found.

This applies only to /FOSTER/bin/tigcmproc.dev. 

--Ben